Naked-eye Detection Of Hg2 Research Articles

Wettability tunable surfaces: Naked-eye detection of Hg2+ based on contact angle variation and colorimetric change

Developing multiple visual signals to reveal comprehensive information of metal ions with simplest operations is attractive and significant for on-site detection. In this paper, wettability tunable surfaces were fabricated to selectively detect Hg2+ ions based on contact angle (CA) variation and colorimetric change. Firstly, hydrophobic nanopin surfaces were fabricated through a chemical bath deposition method and fully characterized by FTIR, XRD, SEM and TEM. Then chitosan stabilized silver nanoparticles (AgNPs) were deposited onto the hydrophobic surfaces to introduce reactants for detecting metal ions. By varying the concentration of AgNPs, the surface wettability can be regulated and the CA are tuned ranging from 152.1 ± 1.0° to 128.9 ± 0.6°. As addition of Hg2+ ions, the CA of AgNPs modified hydrophobic surfaces decrease obviously and surface color changes from brown to white, which are attributed to the vanishment of AgNPs based on the redox reaction between AgNPs and Hg2+ ions and the simultaneously destruction of the nanopin surface structure. A linear relationship between the CA changes and Hg2+ concentration was achieved over the range of 10−6 M–10−2 M and the limit of detection (LOD) is calculated to be 2.6 × 10−7 M. In addition, this strategy was also applied to detect Hg2+ in the real water samples with recoveries ranged from 98.0% to 107.0%. This method introducing both CA variation and colorimetric change as signals provides a new avenue for developing multiple on-site detection signals of metal ions by naked-eye.

Colorimetric and fluorescent multi-ion recognition by Anthracene appended di-Schiff base chemosensor

A new di-Schiff base colorimetric sensor, 4-(Anthracen-9-ylmethylene-hydrazonomethyl)-benzene-1,3-diol (coded as AHB), possessing anthracene and 2,4-dihydroxybenzaldehyde as fluorophore and receptor, respectively, has been reported. The sensor AHB is capable of naked eye detection of Hg2+ ions and detection of Cu2+ and Al3+ ions via two different fluorescence mechanisms in HEPES buffered CH3OH: H2O (9: 1) solvent system. The sensor witnessed high selectivity towards all the three ions in the presence of various other metal ions. The quantitative detection limit of Hg2+ ions was calculated to be 2 μM; while it was 2.07 and 1.29 μM for Cu2+ and Al3+ ions, respectively.

A novel, anthracene-based naked eye probe for detecting Hg2+ ions in aqueous as well as solid state media

A novel di-Schiff base colorimetric sensor, 2-((E)-(((E)-anthracen-9-ylmethylene)hydrazineylidene)methyl)quinolin-8-ol (coded as AQ), connecting anthracene and 8-hydroxyquinaldehyde functionalities is developed for the naked eye detection of Hg2+ ions in HEPES buffered CH3OH: H2O (7: 3) solvent system within neutral pH range. The sensor witnessed high selectivity towards Hg2+ ions in the presence of various other metal ions with naked eye colour change from yellow to pink. The quantitative detection limit of 220 nM was achieved through UV–Vis spectroscopy. The change in the intramolecular charge transfer behaviour of AQ has been proposed to be responsible for the observed absorption as well as colour change as evident from 1H NMR titration, FT-IR studies and DFT calculations. Moreover, the probe AQ has been efficiently applied for the solid state naked eye detection of Hg2+ ions in the form of filter paper strips and solid silica gel (60–120 mesh), pre-impregnated with AQ, and for the detection of Hg2+ ions in real water samples.

A styrylpyridinium dye as chromogenic and fluorogenic dual mode chemosensor for selective detection of mercuric ion: Application in bacterial cell imaging and molecular logic gate

The present work demonstrates design, synthesis and chemosensing application of a styrylpyridinium based donor-π-acceptor (D-π-A) chromophore (L1) containing NS2O2 binding site. The chemosensor L1 selectively and successfully detects Hg2+ ions both visually and spectro-photometrically in perfect aqueous medium as well as in an aqueous-alcoholic mixture. Contrary to the reported literature on mercury sensing by cyanine dye which were reported to be “turn-off” Hg2+ sensor, probe L1 shows fluorescence “turn-on” response. D-π-A chromophore L1 exhibits orange colour in aqueous and aqueous-alcoholic solutions due to intramolecular charge transfer (ICT) from the N, N-disubstitutedaminostyryl donor to pyridinium acceptor moiety. It shows Hg2+-specific colour change with concomitant generation of a new absorption band and large emission enhancement (~10 fold) along with a blue shift of emission peak, owing to the formation of a selective 1: 1 L1-Hg2+ complex. 1H NMR analysis reveals the binding mode of L1 with Hg2+. Hg2+ probing process was found to be reversible in presence of sulphide anion. The reversible off-on-off fluorescence response of the sensor with Hg2+ and S2− has been used to generate an INHIBIT molecular logic gate. The probe not only provides a highly efficient, low cost, portable sensor for recognition and naked-eye detection of Hg2+ with a low detection limit in aqueous solution but its turn-on fluorescence response and cell permeability offer the possibility of using it for fluorescence imaging in living cells.

Unusual seedless approach to gold nanoparticle synthesis: application to selective rapid naked eye detection of mercury(II).

We report a novel seedless Hg(2+)-induced synthetic approach for the preparation of gold nanostructures. This protocol is demonstrated for the highly selective and sensitive naked eye detection of Hg(2+) based on the high affinity metallophilic Hg(2+)-Au(+) interaction. The response time upon exposure to Hg(2+) is almost instantaneous.

Simple, efficient and selective colorimetric sensors for naked eye detection of Hg2+, Cu2+ and Fe3+

Compounds 3 and 4 are all push–pull molecules containing both a donor 1,3-dithiole ring and an acceptor carbonyl group or thiocarboyl group, and their structures confer them with special spectroscopic properties. Their recognition behaviors towards metal ions were explored by UV-vis spectral analysis, and the results showed that combination of 3 and 4 could efficiently detect Hg2+, Cu2+ and Fe3+. The instant color changes induced by the addition of corresponding metal ions make them excellent naked eye sensors for the detection of heavy metal ions.

A chelation enhanced selective fluorescence sensing of Hg2+ by a simple quinoline substituted tripodal amide receptor

Two tris(2-aminoethyl)amine (tren) based tripodal amide fluoroionophores, 1 and 2, functionalized with quinoline (chelating fluorophore) and naphthalene (non-chelating fluorophore) respectively, are synthesized in good yields. Fluoroionophore 1 shows a selective UV-Vis spectral shift in the case of Hg(2+) in acetonitrile among different metal ions like Li(+), Na(+), Ca(2+), Mg(2+), Cr(2+), Mn(2+), Fe(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), Pb(2+), and Ag(+). On the other hand, fluoroionophore 2 shows no selectivity towards any of the above metal ions in the UV-Vis study. Furthermore, 1 shows a selective chelation induced fluorescence enhancement in the presence of Hg(2+) whereas 2 shows the enhancement of fluorescence with most of the metal ions via a photoinduced charge transfer mechanism. The naked eye detection of Hg(2+) in an acetonitrile solution of 1 shows a greenish fluorescence upon UV light irradiation. The isolated Hg(2+) complex of 1, 3, shows a similar UV-Vis and fluorescence spectral output as observed from in situ spectroscopic studies of 1 in the presence of Hg(2+). Infra-red (IR) and (1)H- NMR studies also reveal the interaction of Hg(2+) with the quinoline nitrogen atoms as well as with the amide functionality.

New Azobenzene Dye Colorimetric and Ratiometric Chemosensors for Mercury(II) Ion

AbstractA new series of azobenzene dyes, which possessed colorimetric and ratiometric recognition to Hg2+ based on the mechanism of internal charge transfer (ICT), was developed and characterized. The molecules involving azo and imino functional groups can coordinate with Hg2+ to result in a large blue shift from 453 to 363 nm corresponding to a notable color change from orange to pale yellow in aqueous methanol solution (H2O/CH3OH=1/4, V/V), which can be applied to naked eye detection of Hg2+. The sensitivity, selectivity and binding mode of the sensors to Hg2+ were investigated by UV‐Vis spectroscopy.